Optical fiber unit installation apparatus including a unit for preventing backward flowing of fluid

ABSTRACT

An optical fiber unit installation apparatus having a unit for preventing a fluid from flowing backward toward entrance of the optical unit to prevent fluid leakage while the optical fiber unit is installed using air pressure is disclosed. The apparatus includes an optical fiber unit supplier; a blowing head having an entrance for introduction of an optical fiber unit supplied from the supplier, and an exit communicated with the entrance and combined with a tube for air pressure installation; a pressing unit for applying air pressure to the optical fiber unit introduced into the blowing head to insert the optical fiber unit into the tube; and a fiber sealing unit, an aggregation of fur-type elastic fibers, mounted in an advancing path of the optical fiber unit through the blowing head to prevent fluid leakage by surrounding the optical fiber unit with fiber ends contacted thereon.

TECHNICAL FIELD

The present invention relates to an optical fiber unit installationapparatus, and more particularly to an optical fiber unit installationapparatus having a unit for preventing a fluid from flowing backwardtoward an entrance of the optical fiber unit to prevent a fluid leakagewhile the optical fiber unit is installed using air pressure.

BACKGROUND ART

A method for previously setting up a tube for air pressure installationat an optical fiber installation spot and then installing an opticalfiber unit in the tube by air pressure is very widely used as an opticalfiber installation technique at a narrow space such as FITH (Fiber ToThe Home) since it ensures easy installation and removal of the opticalfiber unit and requires low costs for construction.

FIG. 1 is a perspective view showing an appearance of a general opticalfiber unit for air pressure installation, commonly called as ABF (AirBlown Fiber).

Referring to FIG. 1, the optical fiber unit U includes an optical fiberbundle 10 commonly having 1 to 12 cores, and a buffer coating layer 11formed on the bundle 10. On the surface of the buffer coating layer 11,glass beads 12 are additionally formed to decrease fractional force withthe inner surface of the tube for air pressure installation and increasedrag force caused by the air pressure. When required, a polymer foaminglayer or a Teflon coating layer may be provided on the buffer coatinglayer 11 in order to increase the drag force.

FIG. 2 is a schematic view showing a conventional air pressureinstallation apparatus which inserts the optical fiber unit U configuredas above into a tube by means of air pressure.

Referring to FIG. 2, the conventional optical fiber unit installationapparatus includes an optical fiber unit supplier 20, a blowing head 21having an entrance A into which the optical fiber unit U successivelyprovided from the optical fiber unit supplier 20 is introduced and anexit B communicated with the entrance A and combined with an airpressure installation tube 22, a pressing unit 26 for applying acompressed air to the exit B of the blowing head 21 so that the opticalfiber unit U introduced into the entrance A is inserted into the airpressure installation tube 22, a driving roller unit 23 for pushing theoptical fiber unit U into the air pressure installation tube 22 withrotating on both sides of the optical fiber unit U, and a bucklingsensor 25 for sensing that movement of the optical fiber unit U isprohibited in the tube 22 by an obstacle and then stopping theinstallation.

In the conventional optical fiber unit installation apparatus, theoptical fiber unit U, continuously introduced into the blowing head 21,is inserted and installed in the installation tube 22 by the airpressure provided from the pressing unit 26 with controlling itsadvancing speed by the driving roller unit 23.

Meanwhile, the blowing head 21 has a sealing unit 24 to prevent thecompressed air supplied from the pressing unit 26 from flowing backwardtoward the entrance of the optical fiber unit U. Conventionally, thesealing unit 24 having a shape of such as O-ring is adhered to the outercircumference of the optical fiber unit U in order to effectivelyprevent backward flow of the fluid.

However, the surface of the optical fiber unit U has very weak structuresince the glass beads 12 are formed thereon. Thus, if the sealing unit24 is installed in contact with the outer circumference of the opticalfiber unit U, the surface may be damaged while the optical fiber unit Upasses through the sealing unit 24 during installation.

In such a reason, the sealing unit 24 is not contacted with the outercircumference of the optical fiber unit U but has a predetermined gap.Accordingly, while the air pressure installation is conducted using theconventional optical fiber unit installation apparatus, a significantamount of fluid is flowed backward toward the entrance A and leakedthrough the gap between the sealing unit 24 and the outer circumferenceof the optical fiber unit U, thereby causing noise and deterioratinginstallation performance and efficiency of the pressing unit 26.

DISCLOSURE OF INVENTION

The present invention is designed to solve the problems of the priorart, and therefore an object of the invention is to provide an opticalfiber unit installation apparatus which is provided with a means forpreventing fluid from flowing backward toward an entrance of the opticalfiber unit and leaking out.

In order to accomplish the above object, the present invention providesan optical fiber unit installation apparatus, which includes an opticalfiber unit supplier; a blowing head having an entrance into which anoptical fiber unit supplied from the optical fiber unit supplier isintroduced, and an exit communicated with the entrance and combined withan installation tube for air pressure installation; a pressing unit forapplying air pressure to the optical fiber unit introduced into theblowing head so that the optical fiber unit is inserted into theinstallation tube; and a fiber sealing unit which is an aggregation offur-type elastic fibers mounted in an advancing path of the opticalfiber unit through the blowing head, the fiber sealing unit preventingleakage of fluid by surrounding the inserted optical fiber unit so thatfiber ends thereof are contacted with the optical fiber unit.

The optical fiber unit installation apparatus preferably furtherincludes a driving roller unit for pushing the optical fiber unit intothe installation tube with rotating on both sides of the optical fiberunit.

In the present invention, the fur-type fiber preferably has a functionof eliminating static electricity. In addition, the fur-type fiber ispreferably inclined toward an advancing direction of the optical fiberunit when being provided to the fiber sealing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of preferredembodiments of the present invention will be more fully described in thefollowing detailed description, taken accompanying drawings. In thedrawings:

FIG. 1 is a perspective view showing an appearance of a conventionaloptical fiber unit for air pressure installation;

FIG. 2 is a schematic view showing an optical fiber unit installationapparatus according to the prior art;

FIG. 3 is a schematic view showing an optical fiber unit installationapparatus according to a preferred embodiment of the present invention;

FIG. 4 is a perspective view showing an appearance of a fiber sealingunit of FIG. 3; and

FIG. 5 is a sectional view showing that an optical fiber unit passesthrough the fiber sealing unit of FIG. 3.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail referring to the accompanying drawings. Prior to thedescription, it should be understood that the terms used in thespecification and appended claims should not be construed as limited togeneral and dictionary meanings, but interpreted based on the meaningsand concepts corresponding to technical aspects of the present inventionon the basis of the principle that the inventor is allowed to defineterms appropriately for the best explanation. Therefore, the descriptionproposed herein is just a preferable example for the purpose ofillustrations only, not intended to limit the scope of the invention, soit should be understood that other equivalents and modifications couldbe made thereto without departing from the spirit and scope of theinvention.

FIG. 3 shows an optical fiber unit installation apparatus according to apreferred embodiment of the present invention.

Referring to FIG. 3, the optical fiber unit installation apparatus ofthe present invention includes an optical fiber unit supplier 30, ablowing head 31, a pressing unit 36, and a fiber sealing unit 37.

The optical fiber unit supplier 30 is generally provided with a generaloptical fiber unit U for air pressure installation so that the opticalfiber unit U is wound around a bobbin. The optical fiber unit U providedto the optical fiber unit supplier 30 is supplied to the blowing head 31alone or in multiple, and then inserted and installed in an installationtube 32 for air pressure installation.

The blowing head 31 has an entrance A into which the optical fiber unitU is introduced, and an exit B communicated with the entrance A. At theexit B of the blowing head 31, a general installation tube 32 for airpressure installation is combined. On the while, the pressing unit 36 isconnected to a conduit 31 a diverged from one point between the entranceA and the exit B.

The pressing unit 36 applies air pressure so that the optical fiber unitU is inserted into the installation tube 32. A pressure exerted by thepressing unit 36 is preferably set in the range of 10 to 15 atm, but notlimited in that range. The compressed air generated by the pressing unit36 is introduced into the installation tube 32 via the conduit 31 a ofthe blowing head 31 with applying pressure to the optical fiber unit U.

The blowing head 31 is also provided with a driving roller unit 33 inorder to control an installation speed of the optical fiber unit U. Thedriving roller unit 33 has two rollers which rotate with the opticalfiber unit U interposed therebetween, thereby pushing the optical fiberunit U into the installation tube 32.

Additionally, the blowing head 31 may further include a buckling sensor35 installed around the optical fiber unit U which advances into theinstallation tube 32, for example, on the outer circumference of a guidepipe through which the optical fiber unit U passes. The buckling sensor35 senses an advancing state of the optical fiber unit U. In addition,the buckling sensor 35 detects whether the optical fiber unit U isstopped due to an obstacle or buckled beyond a critical point while theoptical fiber unit U is advancing in the installation tube U. If it is,the buckling sensor 35 makes the driving roller unit 33 stop so that theinstallation of the optical fiber unit U is stopped.

The fiber sealing unit 37 is provided at a point of the blowing head 31,preferably at the entrance A. The fiber sealing unit 37 prevents thecompressed air, which flows into the blowing head 31 through the conduit31 a of the blowing head 31, from partially flowing backward in adirection opposite to the advancing direction of the optical fiber unitU and then leaked out.

An installation position of the fiber sealing unit 37 is not limited tothe drawing, but may be selected in the range between the entrance A ofthe blowing head 31 and a diverging point C. Here, the diverging point Cis a point at which the conduit 31 a starts to diverge from theadvancing path of the optical fiber unit U, which connects the entranceA and the exit B of the blowing head 31.

FIG. 4 shows an appearance of the fiber sealing unit 37 in more detail.

Referring to FIG. 4, the fiber sealing unit 37 is an aggregation of aplurality of fur-type elastic fibers. Preferably, the fiber sealing unit37 is provided on the inner wall of a pipe-type support member 37 a,which composes the entrance A of the blowing head 31 to which theoptical fiber unit U is introduced.

A plurality of the fibers composing the fiber sealing unit 37 arearranged to substantially surround the outer circumference of theintroduced optical fiber unit U, and so that ends of the fur-type fibersare contacted with the surface of the optical fiber unit U. Thus, thefur-type fibers prevent the fluid from flowing backward in a directionopposite to the advancing direction of the optical fiber unit U.

The fur-type fibers which compose the fiber sealing unit 37 arepreferably inclined at a predetermined angle toward the advancingdirection (see an arrow expressed by a solid line in FIG. 5) of theoptical fiber unit U. In this case, the fur-type fibers do not interruptadvancing movement of the optical fiber unit U toward the installationunit 32, and prevents the fur-type fibers from being leaned to adirection opposite to the advancing direction of the optical fiber unitU.

The fiber sealing unit 37 preferably has a function of eliminatingstatic electricity together with dusts formed on the surface of theoptical fiber unit U. For this purpose, the fur-type fiber may be madeof an organic fiber, a polymer fiber or an acrylic fiber, which has astatic electricity eliminating function, but not limitedly.

The fur-type fiber preferably includes carbon or conductive materialssuch as metal or metal ions in order to have the static electricityeliminating function. The fur-type fiber may be a polyethylene fiber ora polypropylene copolymer fiber.

Meanwhile, the blowing head 31 preferably has a sealing member 34 (seeFIG. 3) surrounding the optical fiber unit U, which advances toward theinstallation tube 32, with a predetermined gap in order to preventbackward flow of the fluid more effectively together with the fibersealing unit 37.

Now, operation of the optical fiber unit installation apparatusconfigured as mentioned above according to the present invention isdescribed.

In order to insert the optical fiber unit U into the installation tube32, which is mounted in advance, a compressed air is applied to theblowing head 31 using the pressing unit 36. Then, the optical fiber unitU, which is successively supplied from the optical fiber unit supplier30, advances in the installation tube 32 by means of the pressure of thecompressed air, thereby making the optical fiber unit U be installed. Atthis time, the compressed air supplied into the blowing head 31partially flows backward toward the entrance of the optical fiber unitU. However, since the fiber sealing unit 37 is provided to the blowinghead 31, an amount of compressed air leaked out of the blowing head 31is remarkably reduced.

The fiber sealing unit 37 is composed of an aggregation of fur-typefibers having predetermined elasticity, and substantially contacted withthe advanced optical fiber unit U with the ends of the fur-type fiberssurrounding the outer circumference of the optical fiber unit U. Thefiber sealing unit 37 thus keeps contacting with the surface of theoptical fiber unit U with being inclined to the advancing direction ofthe optical fiber unit U, while not exerting serious pressure to thesurface of the optical fiber unit U., for example to the glass beads 12(see FIG. 1). Thus, a leakage area of the fluid is not generated orgreatly reduced between the optical fiber unit U and the fiber sealingunit 37, so the compressed air leakage phenomenon at the entrance of theoptical fiber unit U is effectively prevented.

In addition, if the fiber sealing unit 37 is composed of fibers having astatic electricity eliminating function such as a carbon fiber or aconductive fiber, the fiber sealing unit 37 may also eliminate staticelectricity charged on the surface of the optical fiber unit U whenbeing contacted with the optical fiber unit U.

INDUSTRIAL APPLICABILITY

The optical fiber unit installation apparatus of the present inventionprevents backward flow and leakage of the fluid with great efficiencysince it has a means for preventing backward flow of the fluid, which iscontacted with the surface of the optical fiber unit without givingserious pressure thereto. Thus, if the apparatus of the presentinvention is applied to the air pressure installation, noise isremarkably reduced during the installation work. In addition, in theaspect of the installation apparatus, many advantageous effects such asreduction of energy consumption and improvement of installationperformance are expected.

Moreover, the installation apparatus of the present invention mayprevent the optical fiber unit characteristics from be deteriorated dueto static electricity by eliminating static electricity on the surfaceof the optical fiber unit while the air pressure installation isconducted.

The present invention has been described in detail. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are given by way ofillustration only, since various changes and modifications within thespirit and scope of the invention will become apparent to those skilledin the art from this detailed description.

1. An optical fiber unit installation apparatus comprising: an opticalfiber unit supplier; a blowing head having an entrance into which anoptical fiber unit supplied from the optical fiber unit supplier isintroduced, and an exit communicated with the entrance and combined withan installation tube for air pressure installation; a pressing unit forapplying air pressure to the optical fiber unit introduced into theblowing head so that the optical fiber unit is inserted into theinstallation tube; and a fiber sealing unit which is an aggregation offur-type elastic fibers mounted in an advancing path of the opticalfiber unit through the blowing head, the fiber sealing unit preventingleakage of fluid by surrounding the inserted optical fiber unit so thatfiber ends thereof are contacted with the optical fiber unit.
 2. Anoptical fiber unit installation apparatus according to claim 1, furthercomprising a driving roller unit for pushing the optical fiber unit intothe installation tube with rotating on both sides of the optical fiberunit.
 3. An optical fiber unit installation apparatus according to claim1, wherein the fur-type fiber has a function of eliminating staticelectricity.
 4. An optical fiber unit installation apparatus accordingto claim 3, wherein the fur-type fiber is an organic fiber or an acrylicfiber.
 5. An optical fiber unit installation apparatus according toclaim 3, wherein the fur-type fiber is a polymer fiber.
 6. An opticalfiber unit installation apparatus according to claim 5, wherein thepolymer fiber contains carbon, metal or metal ion.
 7. An optical fiberunit installation apparatus according to claim 5, wherein the polymerfiber is a polyethylene or polypropylene copolymer.
 8. An optical fiberunit installation apparatus according to claim 1, wherein the fur-typefiber is inclined toward an advancing direction of the optical fiberunit.